ScalaTest is the most flexible and most popular testing tool in the Scala ecosystem.
With ScalaTest, you can test Scala, Scala.js (JavaScript), and Java code.
By offering deep integration with tools
such as JUnit, TestNG, Ant, Maven, sbt, ScalaCheck, JMock, EasyMock, Mockito, ScalaMock, Selenium, Eclipse, NetBeans, and IntelliJ,
ScalaTest makes it easy to take your testing to a higher, more productive level in new or existing Scala, Scala.js, or Java projects.

Like the Scala language on which it is built, ScalaTest is
designed to grow with the demands of its users: You can easily extend and compose ScalaTest's core components
to address just about any special requirements you may have. As a result, ScalaTest can scale to projects of all sizes, from
an individual exploring a new idea to large teams collaborating on mission-critical software.

One way ScalaTest scales down is that despite its rich feature set, ScalaTest is easy to get into. Building on what you already know
from experience with other test frameworks, you can become productive with ScalaTest very quickly.

To maximize your productivity, ScalaTest uses its own extension points to support several styles of testing out of the box.
You can select whatever style best fits your team's experience and culture. For instance, the above example
uses FlatSpec, a good choice for teams wishing to move from XUnit to BDD. When
you run it, you get an informal specification of the software being tested:

ScalaTest does not try to impose a testing philosophy on you, but rather is designed from the philosophy that
the tool should get out of your way and let you work the way you find most productive.
If FlatSpec doesn't meet your team's needs, that's not a problem. ScalaTest has several other styles to choose from.

In short, ScalaTest
is a workbench providing many small, focused tools you can compose together to solve the problems you
face today, yet grow with you as your needs change tomorrow.